1. Field of the Invention
The present invention relates to an actuator capable of being moved to draw an operating pin along an axial direction while being operated and relates to an actuator which when being operated needs to enable an operating pin to be operated instantaneously, such as one utilized for controlling pressure inside of an airbag or controlling the shape of an airbag which is mounted in a vehicle.
2. Description of the Related Art
There is an actuator of a related art shown in US Patent Publication No. 2002/0135166. According to the actuator of the related art, a piston held inside of a cylinder case to project an operating pin outward is moved rearward inside of the cylinder case along with the operating pin by utilizing a driving gas generated when a squib provided at the piston is operated. Further, in the actuator of the related art, the cylinder case is provided with a side wall portion surrounding the piston and a ceiling wall portion closing the front end side of the side wall portion and projecting the operating pin outward. When operated, the squib is constituted to inject the driving gas into the cylinder case from an injection hole formed at a cap portion of the piston arranged to cover the squib. Further, the operating pin projected from the ceiling wall portion is constituted to move rearward along with the piston by means of the driving gas injected from the injection hole of the cap portion when the squib is operated. Further, in the actuator of the related art, the piston is contained inside of the cylinder case which is kept by a positioning member from moving rearward before being operated.
However, according to the actuator of the related art, only the rearward movement of the piston before being operated is restricted by the positioning member arranged at a position where it is exposed outward from the cylinder case constituting a front end side of the operating pin. Therefore, the piston is liable to be moved before being operated and forward movement of the piston cannot firmly be restricted until it is operated. Further, in the actuator of the related art, the injection hole provided at the cap portion of the piston is constituted to inject the driving gas along a direction orthogonal to an axis of the operating pin. Further, in the actuator of the related art, the injection hole is disposed at a vicinity of the ceiling wall portion of the cylinder case before the actuator is operated. Therefore, when the piston is moved forward before operation, there is a concern that the injection hole will move toward the ceiling wall portion and be closed by the ceiling wall portion, and so there is a room for improvement to ensure that the driving gas is swiftly injected from the injection hole and the operating pin is swiftly moved rearward upon operation.